1. Field of the Invention
The present invention generally relates to projecting two-dimensional images of large size, especially using single mode laser sources or multimode laser sources, to reducing speckle noise, to creating three-dimensional displays, and to minimizing cross-coupled signals in drive mechanisms and pick-up mechanisms used in image projection.
2. Description of the Related Art
It is generally known to project a two-dimensional image on a screen based on a pair of scan mirrors which oscillate in mutually orthogonal directions to scan a laser beam over a raster pattern. However, the known image projection systems project an image of limited resolution, typically less than a fourth of video-graphics-array (VGA) quality of 640×480 pixels, and of limited size. In the case of a color image formed by laser beams of different wavelengths (colors), some laser sources, for example, red semiconductor single mode lasers have insufficient power to produce a color image of uniform brightness. The use of multimode red lasers having higher power is however restricted by their highly divergent laser beams. Speckle noise, which is caused by the coherent nature of laser light, is an omnipresent problem that detracts from good display quality. The known projected images are two-dimensional, which lacks the greater realism of a three- dimensional display. Also, the known drive mechanisms used to oscillate the scan mirrors are identical to pick-up mechanisms used to generate positional information from the oscillating mirrors. These identical mechanisms result in cross-coupled signals which lead to noise and distortion.